Muscle Dysfunction in Patients With Chronic Obstructive Lung Disease (COPD): the Role of Sympathetic Activation

The objective of the project is to better understand the causes of exercise limitation, dyspnea and neurohumoral activation in patients with COPD. In particular, the investigators aim to explore the mutual interaction of neurohumoral activation and exercise limitation thereby focussing on differential effects of the peripheral muscle and the diaphragm. Eventually the findings might influence treatment modalities. If sympathetic activation contributes to exercise limitation then drugs influencing the autonomic nervous system would be a reasonable therapeutic concept. If a reduction of sympathetic activity due to an alteration of the ergoreflex can be achieved by non-invasive ventilation this would help to improve dyspnea and exercise capacity.

Our aim is to investigate whether reduced exercise capacity, increased respiratory drive and dyspnoea are linked to heightened sympathetic activation at rest and during exercise in patients with COPD. Furthermore, the effect of unloading the respiratory muscles by using non-invasive ventilation (NIV) will be assessed. Fifteen stable COPD patients without NIV will be matched to 15 healthy control subjects (with sufficient microneurography recording). Furthermore COPD patients on regular NIV will be studied. Each participant will undergo symptom limited bicycle exercise and a handgrip protocol. Microneurography will be used to quantify sympathetic activity by the transcutaneous registration of postganglionic sympathetic efferents.